Closed circuit fire and burglar alarm



June 10, 1952 H. G. FORRESTER CLOSED CIRCUIT FIRE AND BURGLAR ALARM FiledAug. so, 1950 IN VEN TOR. Herman [brre ser ATTD R N EYE Patented June 10, 1952 CLOSED CIRCUIT FIRE BURGLAR ALARM HermanGxForrester, Chattanooga, Tenn. Application August 30, 1-950,S,erial No. 182,344

3 "Claims. (015-177-356) This invention relates to alarm devices of the closed circuit type and in particular includes an auxiliary battery alarm circuit and amaincirlcuit fed through .a. step-down transformer with a relay inthe maincircuit for closing the auxiliary circuit and also with control board lights connected inparallel with fusible and breakable elements of lower resistance than the lights whereby upon breakage of an element the current passes through and lights the light associated therewith, also actuating the relay to close the auxiliary .circuit whereby an indicating light is provided and an audible signal device is also actuated.

The purpose of this invention is to provide a closed circuit alarm device that includes a signal light indicating that the circuit is operating satisfactorily and which, when trouble develops provides alight indicating where the trouble is and also sounds an alarm.

Numerous types of burglar alarm circuits have been provided of both the open and closed types but .it is difficult to provide a positive actuated circuit that is dependable under all conditions that may be installed in the average household at a reasonable cost. With this thought in mind this invention contemplates a circuit containing fusible andbreakable elements connected through signal lights that are not lighted until the 'elements are broken and an audible alarm with a battery circuit and actuated by the main circuit upon breaking of an element therein and the entire device .may be installed in :a residence by the average layman and plugged into the conventional lighting circuit at a suitable point.

The object of this invention is, therefore, to"

provide means for connecting fusible and breakable elements in combination with signal lights with a "pilot light connected across a resistance in thecircuit and with an audible alarm in a battery circuit adaptedto be closed upon breaking" of one of the elements.

Another object of the invention is to provide a closed circuit for fire and burglar alarms that operates with a minimum amount of current.

A further'object of the invention is to provide a closed circuit fire and burglar alarm that is suitable for the average household which is of a simple and economical construction.

Other features and advantages of the invention will appear from the following description taken in connection with the drawings wherein the drawing shows a typical wiring diagram with the elements connected therein.

Referring now to the drawings wherein ilike reference characters denote corresponding parts the improved closed circuit alarm of this invention includes .a transformer 10 having a primary winding II and a low voltage secondary winding l2, a main circuit closing switch IS, a bell M for providing :an audiblesignal, a plurality of lights provided with terminals :25 and 26 that are positioned to be closed by a contact bar .21 of the switch l3.

The switch i3 is also provided with a contact bar 28 which, when closed, closes a circuit to terminals 29 and 30 ofan auxiliary circuit, the termina129 being connected by a wire 3| to a battery 32 and to the terminal of an audible signal H "by a wire 33. The opposite terminal of the alarm 14 is connected by a. wire 3'4 to a contact 35 which is positioned to be engaged by a contact arm33 of a solenoid of the relay IT. The bar 36 is also positioned to engage a contact 31 of a wire 38 that extends to the terminal 30 whereby upon deenergization of the relay 1! the core of the relay is actuated by a spring 39 to move the bar 36 against contact points 35 and 31 so that the current is closed through the bell or audible signal M.

One end of the secondary winding IQ of the transformer I0 is connected to one side of the relay 1! by wires '49 and and the light It! is connected between the wires 49 and 45 whereby the light will show continuously when the switch I6 is closed indicating that the alarm circuit is operating satisfactorily. The variable resistor I9 is connected across the wires 66 and ll by wires 42 and 13 for regulating the current passing through the system whereby the resistance of the light 1- 5 in proportion to that of the elements 16 is such that the lights will not light until the element associated with the light is broken.

From the opposite terminal of the relay I? a wire W4 extends to a point 65 on a terminal board 46 and "from this terminal a wire 41, in which the lights ["5 and 2 are positioned extends across to :a "point 1'8 that is connected to the opposite side of the low voltage secondary l2 by a wir 49.

The=elements l t, which may be formed of Wire, wire loops, ioil "on panes of glass, or microswitches are connected across the terminals of lights '-I 5 by wiresand 5| and as long as these elements are intact, the resistance thereof shorts out the lights 1 5 and the lights 15 will not light. Upon'breakage of one of the elements I 6 the circuit instantly passes through the light I5 associated therewith so that the light will light, and "as the resistance of the light is too high to im- :pose sufiicient load to hold the relay I i open, the relay becomes deenerg'ized and the spring 39 :snaps the contact bar-535 against the points 35 and 31, closing the auxiliary battery circuit and sounding the alarm.

It will be, understood that as many of the lights l may be used as may be desired and the corresponding elements 16 may be placed on doors, windows and the like, and these may also be located in a kitchen, bedroom, or garage. Similar elements may also be installed at different points throughout the residence or building.

The system is also provided with a plurality of fusijble elements 20, that may be positioned at various points throughout a building, which when fused by heat, break a circuit, lighting the light 2|, similar to one of the lights I5 and also deenergizing the relay ll whereby the auxiliary circuit is completed. and the alarm sounded.

The fire alarm circuit includes a wire 52 ex tended from the terminal 45 and a return wire 53 which is connected to a terminal 54 and from this terminal the circuit is connected to a wire 39 of the secondary i2 by a wire 55 which is provided with a switch 5%. With the switch 59 open the fire alarm circuit operates similar to one of the circuits through one of the elements It and when it is desired to cut out the circuits through the elements it and light 15, such as during the day, the switch 58 is closed whereby only the fire alarm circuit is in operation.

voltage side of the By this means it is possible to provide fusible and also breakable elements at different points through a building and with a closed circuit through these elements the pilot light will be lighted to show that the circuit is in operation and should one of the breakable or fusible elements be destroyed, a light will be provided indicating the location of the destroyed element and at the same time an audible alarm, such as the bell M will be sounded.

This alarm circuit therefore provides positive protection at comparatively low cost.

It will be understood that modifications may be made in the design and arrangement of the parts without departing from the spirit of the invention.

What is claimed is:

1. An alarm circuit comprising a step down transformer, a plug extended from the high voltage side of the transformer for connecting the transformer to a source of current supply, a double knife switch positioned with one of said knives in the connection from the transformer to the plug, an. auxiliary circuit having a battery therein connected to the other knife of the switch and adapted to be closed by switch, an

audible signal in said auxiliary circuit, a pair of open contacts in said auxiliary circuit, a relay positioned to close the said open contacts of the auxiliary circuit, a breakable element, a low voltage circuit extended from the secondary of the transformer to the said breakable element, a signal light connected across the low voltage circuit of the breakable element, the resistance of said signal light being such that upon rupture of the breakable element the signal light will light, a variable resistance in the said low voltage circuit, and a pilot light in the said low voltage circuit connected across the said variable resistance, said low voltage circuit being connected to the terminals of the said relay whereby with current in the low voltage circuit the relay holds the said auxiliary circuit open.

2. An alarm circuit comprising a step down transformer, a plug extended from the high voltage side of the transformer for connecting the transformer to a source of current supply,

a double knife switch positioned with one of said knives in the connection from the transformer to the plug, an auxiliary circuit having a battery therein connected to the other knife of the switch and adapted to be closed by said switch, an audible signal in said auxiliary circuit, a pair of open contacts in said auxiliary circuit, a relay positioned to close the said open contacts of the auxiliary circuit, a breakable element, a low voltage circuit extended from the secondary of the transformer to the said breakable element, a signal light connected across the low voltage circuit of the breakable element, the resistance of said signal light being such that upon rupture of the breakable element the signal light will light, a variable resistance in the said low voltage circuit, a pilot light in the said low voltage circuit connected across the said variable resistance, said low voltage circuit being connected to the terminals of the said relay whereby with current in the low voltage circuit the relay holds the said auxiliary circuit open, a fusible element in said low voltage circuit, and a signal light connected across the said fusible element.

3. An alarm circuit comprising a step down transformer, a plug extended from the high transformer for connecting the transformer to a source of current supply, a double knife switch positioned with one of said knives in the connection from the transformer to the plug, an auxiliary circuit having a battery therein connected to the other knife of the switch and adapted to be closed by said switch, an audible signal in said auxiliary circuit, a pair of open contacts in said auxiliary circuit, a relay positioned to close the said open contacts of the auxiliary circuit, a breakable .element, a low voltage circuit extended from the secondary of the transformer to the said breakable element, a plurality of signal lights, a signal light connected across the low voltage circuit of the breakable element, the resistance of said signal lights being such that upon rupture of one of the breakable elements the signal light will light, a variable resistance in the said low voltage circuit, a pilot light in the said low voltage circuit connected across the said variable resistance, said low voltage circuit being connected to the terminals of the said relay whereby with current in the low voltage circuit the relay holds the said auxiliary circuit open, fusible elements in said low voltage circuit, signal lights connected across the said fusible elements, and a circuit with a switch therein connected across the said low voltage circuit for cutting out the circuit to the breakable elements and signal lights associated therewith.

HERMAN G. FORRES'IER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 933,197 Nolen Sept. '7, 1909 1,536,192 Derby May 5, 1925 2,064,533 Grant, Jr. Dec. 15, 1936 2,488,622 Giorgianni Nov. 22, 1949 FOREIGN PATENTS Number Country Date 289,934 Germany Jan. 28, 1916 

